1) Field of the Invention
The present invention relates to a structured lighting material, a method to generate incoherent luminescence employing the structured lighting material, and an illuminator comprising the structured lighting material which emits light when energy is externally applied thereto.
2) Description of the Related Art
To date, various luminescent devices have been developed which emit light in response to energy being externally applied thereto (for example, using an electron beam). Such luminescent devices have come into widespread use in display applications using a cathode-ray tube, a projection tube or the like (ef. Phosphor Handbook, by S. Shionoya and W. M. Chen, CRC Press, Boca Raton, Fla., 1998). The present invention concerns a specific structured lighting material to be used in a luminescent device as described below.
A description will be given hereinbelow of a conventional luminescent device with reference to FIGS. 11(A) and 11(B). A luminescent device comprises a metal-made substrate (base) 102 and a luminescent unit 103 made by placing a phosphor on the substrate 102 in the form of a layer.
In such a configuration, the luminescent device emits light when the host of a phosphor constituting the luminescent unit 103 is excited by electric energy such as electron beam, electric charge or electric field applied from the external. Thus, the luminescent device can convert the inputted electric energy (excitation energy) into luminescence to be outputted.
Although the luminescence or emission intensity of the luminescent device generally increases monotonically with an increase in an excitation energy inputted from the external, the degree of increase is prone to drop if the excitation energy quantity exceeds an energy quantity; if the excitation energy quantity further increases, the luminescent intensity reaches a saturation or decreases (cf. Phosphor Handbook, by S. Shionoya and W. M. Yen, CRC Press, Boca Raton, Fla., 1998, p.489-p.498). When a correlation between electron beam current (current value) A acting as excitation energy and luminescence intensity are shown on a log-log graph and the inclination (which will be referred to hereinafter as an xe2x80x9cinput-output differential variationxe2x80x9d) xcex8[=xcex94 log(I)/xcex94 log(A)] of the line representing this correlation assumes a positive value, it is referred to as a monotonic increase.
The input-output differential variation of the conventional luminescent device is apt to get worse as the input energy such as electron beam increases.
The present invention has been developed in consideration of such a situation, and it is therefore an object of the invention to provide a structured lighting material wherein luminescent intensity increases superlinearly when excitation energy based on electron beam, electric charge or electric field exceeds a threshold.
In the present invention, the term xe2x80x9csuperlinearlyxe2x80x9d signifies that the input-output differential variation xcex8 increases when applied energy exceeds a threshold. In most cases, when the applied energy is below the threshold, the input-output differential variation xcex8 assumes less than 1. On the other hand, it becomes 1 or more when the applied energy is above the threshold.
For this purpose, a structured lighting material according to the first aspect of the present invention is characterized by comprising a luminescent unit wherein the intensity of incoherent luminescence increases superlinearly when energy applied in a non-contact manner exceeds a threshold.
This arrangement, wherein the luminescent intensity of the luminescent unit increases superlinearly when the electric energy given in a non-contact manner exceeds the threshold, can be incorporated into a wide range of applications. For example, the application to various types of illuminations is feasible owing to its high-efficient luminescence. As a further advantage, it is also applicable to detection equipment, alarm equipment or the like because the magnitude of the electric energy can be monitored from the luminescence intensity of the luminescent unit. Furthermore, the application to memories or various types of control devices becomes feasible because the luminescent intensity varies rapidly around a threshold so that the variation of the luminescent intensity is extracted as on/off signals in a state where reference is set to the threshold.
In accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent color of the luminescent unit varies as the input energy increased beyond the threshold.
This provides easy visual confirmation of the variation of the state of the luminescent unit.
In accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the energy is electric energy originating from any one of electron beam, electric charge and electric field.
This allows an energy applying means in a conventional structured lighting material (such as a conventional luminescent device) to be available as it is.
In accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent part has a non-electrical conductive property.
This can provide advantages of securing electrification property of the luminescent unit, generating rapid increase of the luminescent intensity beyond a threshold and effective variation of luminescent color, and developing such variation in the intensity and color of the luminescent unit with low applied energy.
A structured lighting material according to the second aspect of the present invention is characterized by comprising a luminescent unit which shows a non-electrical conductive property and has a microscopic or minute uneven surface, wherein the luminescent intensity increases superlinearly when energy applied to the minute uneven surface in a non-contact manner exceeds a threshold.
The effects similar to those of the structured lighting material according to the first aspect of the invention are attainable, because the luminescent intensity of the luminescent unit increases superlinearly and the luminescent color of the luminescent part varies, when electric energy applied to the minute uneven surface in a non-contact manner exceeds the threshold.
In addition, the luminescent intensity higher than that of a conventional structured lighting material is assured, which realize a high-output illuminator.
Still additionally, the requirement for the luminescent unit is only the realization of the minute uneven surface, and various kinds of knowledge concerned with the conventional structured lighting materials can be put directly to practical use.
In accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, the minute uneven surface is formed in a manner that the thickness of the luminescent unit is made non-uniform.
This allows easy formation of the minute uneven surface simply by making the thickness of the luminescent unit non-uniform. The effects similar to those of the structured lighting material according to the second aspect of the invention are attainable.
In accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, the minute uneven surface has high and low portions respectively corresponding to maximum and minimum thicknesses of the luminescent unit, and the maximum thickness is set to be three or more times said minimum thickness.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is assured.
In addition, in accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, the minute uneven surface has high and low portions respectively corresponding to maximum and minimum thicknesses of the luminescent unit, and the maximum thickness is set to be ten or more times said minimum thickness.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is more assured.
Still additionally, in accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, the minimum thickness of the luminescent unit is not more than 500 xcexcm.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is assured.
Furthermore, in accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, the minimum thickness of the luminescent unit is not more than 50 xcexcm.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is more assured.
Still moreover, in accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, an inclination angle (slope angle) of an uneven surface of a local site is in a range from 30 degrees to 150 degrees.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is assured.
Yet moreover, in accordance with a further feature of the present invention, in the structured lighting material stated above as the second aspect of the invention, an inclination angle of an uneven surface of a local site is in a range from 50 degrees to 130 degrees.
This makes the unevenness of the luminescent unit surface effective, and the effects similar to those of the above-mentioned structured lighting material is more assured.
Furthermore, in accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent unit is made of inorganic material.
Accordingly, this realizes less degradation while the energy is applied thereto.
Still furthermore, in accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent unit is adhered on a substrate.
This allows the luminescent unit to be formed in a stable condition.
Yet furthermore, in accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent unit is adhered on a substrate without using water-soluble fixing agent.
This secures the electrification property of the luminescent unit, and the effects similar to those of the above-mentioned structured lighting material are attainable.
Moreover, in accordance with a further feature of the present invention, in the structured lighting material stated above as the first aspect of the invention, the luminescent unit is adhered on the substrate in a manner of facilitating electrification.
This secures the electrification property of the luminescent unit. The effects similar to those of the above-mentioned structured lighting material are attainable.
Still moreover, an illuminator according to the third aspect of the present invention is characterized by comprising the structured lighting material according to the first or second aspects of the present invention.
This provides efficient luminescence for supplied energy.
In addition, a method to generate incoherent luminescence according to the fourth aspect of the present invention is characterized by applying energy more than a threshold to the structured lighting material including a luminescent unit wherein the intensity of incoherent luminescence increases superlinearly when energy applied in a non-contact manner exceeds the threshold.
This offers the effects similar to those of the structured lighting materials according to the first and second aspects of the present invention.